Prohibition of Self-Purification (Tazkiyah) in the Holy Quran

﴿ إِنَّ ٱللَّهَ لَا يَغۡفِرُ أَن يُشۡرَكَ بِهِۦ وَيَغۡفِرُ مَا دُونَ ذَٰلِكَ لِمَن يَشَآءُۚ وَمَن يُشۡرِكۡ بِٱللَّهِ فَقَدِ ٱفۡتَرَىٰٓ إِثۡمًا عَظِيمًا * أَلَمۡ تَرَ إِلَى ٱلَّذِينَ يُزَكُّونَ أَنفُسَهُمۚ بَلِ ٱللَّهُ يُزَكِّي مَن يَشَآءُ وَلَا يُظۡلَمُونَ فَتِيلًا ﴾ [An-Nisā’: 48-49]

(48) Indeed, Allah does not forgive association with Him, but He forgives what is less than that for whom He wills. And he who associates others with Allah has certainly fabricated a tremendous sin.

(49) Have you not seen those who claim themselves to be pure? Rather, Allah purifies whom He wills, and injustice is not done to them, [even] as much as a thread [inside a date seed].

Surah: An-Nisā’ - Verse: 48-49 - Juz: 5 - Page: 86

﴿ٱلَّذِينَ يَجۡتَنِبُونَ كَبَٰٓئِرَ ٱلۡإِثۡمِ وَٱلۡفَوَٰحِشَ إِلَّا ٱللَّمَمَۚ إِنَّ رَبَّكَ وَٰسِعُ ٱلۡمَغۡفِرَةِۚ هُوَ أَعۡلَمُ بِكُمۡ إِذۡ أَنشَأَكُم مِّنَ ٱلۡأَرۡضِ وَإِذۡ أَنتُمۡ أَجِنَّةٞ فِي بُطُونِ أُمَّهَٰتِكُمۡۖ فَلَا تُزَكُّوٓاْ أَنفُسَكُمۡۖ هُوَ أَعۡلَمُ بِمَنِ ٱتَّقَىٰٓ ﴾ [An-Najm: 32]

(32) Those who avoid the major sins and immoralities, only [committing] slight ones. Indeed, your Lord is vast in forgiveness. He was most knowing of you when He produced you from the earth and when you were fetuses in the wombs of your mothers. So do not claim yourselves to be pure; He is most knowing of who fears Him.

Surah: An-Najm - Verse: 32 - Juz: 27 - Page: 527